Plugin dependencies loading.

backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/internal/plugin/JarPluginLoaderImpl.kt

@@ -26,6 +26,7 @@ import net.mamoe.mirai.utils.info
 import java.io.File
 import java.net.URLClassLoader
 import java.util.concurrent.ConcurrentHashMap
+import java.util.concurrent.ConcurrentLinkedQueue
 
 internal object JarPluginLoaderImpl :
     AbstractFilePluginLoader<JvmPlugin, JvmPluginDescription>(".jar"),
@@ -43,7 +44,7 @@ internal object JarPluginLoaderImpl :
     override val dataStorage: PluginDataStorage
         get() = MiraiConsoleImplementationBridge.dataStorageForJarPluginLoader
 
-    internal val classLoaders: MutableList<ClassLoader> = mutableListOf()
+    internal val classLoaders: ConcurrentLinkedQueue<JvmPluginClassLoader> = ConcurrentLinkedQueue()
 
     @Suppress("EXTENSION_SHADOWED_BY_MEMBER") // doesn't matter
     override val JvmPlugin.description: JvmPluginDescription
@@ -70,7 +71,7 @@ internal object JarPluginLoaderImpl :
         val filePlugins = this.filterNot {
             pluginFileToInstanceMap.containsKey(it)
         }.associateWith {
-            URLClassLoader(arrayOf(it.toURI().toURL()), MiraiConsole::class.java.classLoader)
+            JvmPluginClassLoader(arrayOf(it.toURI().toURL()), MiraiConsole::class.java.classLoader, classLoaders)
         }.onEach { (_, classLoader) ->
             classLoaders.add(classLoader)
         }.asSequence().findAllInstances().onEach { loaded ->

backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/internal/plugin/JvmPluginClassLoader.kt

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2019-2020 Mamoe Technologies and contributors.
+ *
+ * 此源代码的使用受 GNU AFFERO GENERAL PUBLIC LICENSE version 3 许可证的约束, 可以在以下链接找到该许可证.
+ * Use of this source code is governed by the GNU AFFERO GENERAL PUBLIC LICENSE version 3 license that can be found via the following link.
+ *
+ * https://github.com/mamoe/mirai/blob/master/LICENSE
+ *
+ */
+
+@file:Suppress("MemberVisibilityCanBePrivate")
+
+package net.mamoe.mirai.console.internal.plugin
+
+import java.net.URL
+import java.net.URLClassLoader
+import java.util.concurrent.ConcurrentHashMap
+
+internal class JvmPluginClassLoader(
+    urls: Array<URL>,
+    parent: ClassLoader?,
+    val classloaders: Collection<JvmPluginClassLoader>
+) : URLClassLoader(urls, parent) {
+    private val cache = ConcurrentHashMap<String, Class<*>>()
+
+    companion object {
+        init {
+            ClassLoader.registerAsParallelCapable()
+        }
+    }
+
+    // private val
+
+    override fun findClass(name: String): Class<*> {
+        return findClass(name, false) ?: throw ClassNotFoundException(name)
+    }
+
+    internal fun findClass(name: String, disableGlobal: Boolean): Class<*>? {
+        val cachedClass = cache[name]
+        if (cachedClass != null) return cachedClass
+        kotlin.runCatching { return super.findClass(name).also { cache[name] = it } }
+        if (disableGlobal)
+            return null
+        classloaders.forEach { otherClassloader ->
+            if (otherClassloader === this) return@forEach
+            val otherClass = otherClassloader.findClass(name, true)
+            if (otherClass != null) return otherClass
+        }
+        return null
+    }
+}